Drugs for treating various dermal ulcers include ointments, skin cleaning solutions, powders of water-absorbing high polymers, wound-covering patches and so on. These drugs contain, as active ingredients, an antibiotic, an antimicrobial, an enzyme, etc. In particular, ointments having water absorbing and drying properties are frequently applied to the affected skin area having exudate, such as dermal ulcers. The water absorbing and drying properties mean high hygroscopicity for absorbing and removing vulnerary water on the skin.
cAMP derivatives are known to be useful for treating various dermal ulcers as described, e.g., U.S. Pat. No. 4,873,227. The most effective bases with which the cAMP derivatives are applied to the treatment of various dermal ulcers are considered to be those having the above-mentioned water absorbing and drying properties.
However, since water-absorbing and drying bases contain water, when a hydrolyzable drug, such as a cAMP derivative, is combined therewith, the hydrolyzable drug has poor stability and the water-absorbing and drying base can hardly be used for an extended period of time. It has, therefore, been demanded to develop ointments comprising a cAMP derivative and a water-absorbing and drying base in which the cAMP derivative is stable.
It has been suggested to stabilize the cAMP derivative-containing ointments by incorporating sugars and/or inorganic high polymers therein as disclosed in U.S. Pat. No. 5,096,891. However, the stability achieved is still insufficient, needing further improvements.